diff --git a/openevolve/controller.py b/openevolve/controller.py
index b87fdf809..6b6a00684 100644
--- a/openevolve/controller.py
+++ b/openevolve/controller.py
@@ -262,7 +262,7 @@ async def run(
         Returns:
             Best program found
         """
-        max_iterations = iterations or self.config.max_iterations
+        max_iterations = self.config.max_iterations if iterations is None else iterations
         # Determine starting iteration
         start_iteration = 0
         if checkpoint_path and os.path.exists(checkpoint_path):
diff --git a/tests/test_run_iteration_budget.py b/tests/test_run_iteration_budget.py
new file mode 100644
index 000000000..b3c5d5910
--- /dev/null
+++ b/tests/test_run_iteration_budget.py
@@ -0,0 +1,104 @@
+"""Public run iteration budgets must bound the work submitted to the scheduler."""
+
+import tempfile
+import unittest
+from concurrent.futures import Future, ProcessPoolExecutor
+from contextlib import ExitStack
+from pathlib import Path
+from unittest.mock import AsyncMock, Mock, patch
+
+from openevolve.config import Config
+from openevolve.controller import OpenEvolve
+from openevolve.database import Program
+from openevolve.process_parallel import SerializableResult
+
+
+class TestRunIterationBudget(unittest.IsolatedAsyncioTestCase):
+    def setUp(self):
+        workspace = tempfile.TemporaryDirectory()
+        self.addCleanup(workspace.cleanup)
+        self.workspace = Path(workspace.name)
+        self.initial_code = "def solve(): return 0\n"
+        initial_program = self.workspace / "initial.py"
+        initial_program.write_text(self.initial_code)
+
+        config = Config()
+        config.max_iterations = 3
+        config.database.in_memory = True
+        config.database.num_islands = 1
+        config.evaluator.parallel_evaluations = 1
+        config.checkpoint_interval = 100
+
+        evaluator = Mock()
+        evaluator.evaluate_program = AsyncMock(return_value={"combined_score": 0.0})
+        evaluator.get_pending_artifacts.return_value = None
+        self.evaluator = evaluator
+
+        self.executor = Mock(spec=ProcessPoolExecutor)
+        self.executor.submit.side_effect = self.complete_iteration
+        patches = ExitStack()
+        self.addCleanup(patches.close)
+        patches.enter_context(
+            patch("openevolve.process_parallel.ProcessPoolExecutor", return_value=self.executor)
+        )
+        patches.enter_context(patch("openevolve.controller.Evaluator", return_value=evaluator))
+        patches.enter_context(patch("openevolve.controller.LLMEnsemble"))
+        patches.enter_context(patch("openevolve.controller.signal.signal"))
+        patches.enter_context(patch.object(OpenEvolve, "_setup_logging"))
+
+        self.controller = OpenEvolve(
+            initial_program_path=str(initial_program),
+            evaluation_file=str(self.workspace / "unused_evaluator.py"),
+            config=config,
+            output_dir=str(self.workspace / "output"),
+        )
+
+    @staticmethod
+    def complete_iteration(worker, iteration, snapshot, parent_id, inspiration_ids):
+        """Replace worker execution with a completed synthetic result."""
+        program = Program(
+            id=f"child_{iteration}",
+            parent_id=parent_id,
+            code=f"def solve(): return {iteration}\n",
+            metrics={"combined_score": float(iteration)},
+            iteration_found=iteration,
+        )
+        future = Future()
+        future.set_result(
+            SerializableResult(
+                child_program_dict=program.to_dict(),
+                parent_id=parent_id,
+                iteration=iteration,
+                target_island=snapshot["sampling_island"],
+            )
+        )
+        return future
+
+    async def test_zero_only_evaluates_initial_program(self):
+        best = await self.controller.run(iterations=0)
+
+        self.executor.submit.assert_not_called()
+        self.evaluator.evaluate_program.assert_awaited_once_with(self.initial_code, best.id)
+        self.assertEqual(best.code, self.initial_code)
+        self.assertEqual(best.iteration_found, 0)
+        self.assertEqual(len(self.controller.database.programs), 1)
+
+    async def test_none_uses_configured_iterations(self):
+        best = await self.controller.run(iterations=None)
+
+        self.assertEqual(self.executor.submit.call_count, 3)
+        self.assertEqual([call.args[1] for call in self.executor.submit.call_args_list], [1, 2, 3])
+        self.evaluator.evaluate_program.assert_awaited_once()
+        self.assertEqual(best.id, "child_3")
+
+    async def test_positive_iterations_override_config(self):
+        best = await self.controller.run(iterations=1)
+
+        self.executor.submit.assert_called_once()
+        self.assertEqual(self.executor.submit.call_args.args[1], 1)
+        self.evaluator.evaluate_program.assert_awaited_once()
+        self.assertEqual(best.id, "child_1")
+
+
+if __name__ == "__main__":
+    unittest.main()